Negative-pole accumulator-electrod.



E. s oKAL. NEGATIVE POLE AGGUMULATOR ELEGTRODE.

APPLIOATION FILED AUGJZ, 1907.

Patented Dec. 1, 1908.

2 SHEETS-SHEET l E. SOKAL.

NEGATIVE POLEA AGGUMULATOR BLBCTRQDR 'APPLICATION FILBD'AUG. Z, 1907.

Patented Dec. 1, 19,08.

2 SHEETS-SHEET 2.

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l EDWARD SOKAL. OF CHICAGO- ILLINOIS.

NEGATIYILPOLE ACGUMULATOR-ELE CfIIROI` No. 90.54599.v

Specification of Letters Patent,

Patenced'nec. 1, 190s,

Application led August 22, 1907. Serial No. 389,683.

` To all 'whom it may concern.'

vzen of Austria-Hungary, and resident of Chicago, Cook county, Illinois, have invented a inert substances.

certainnew and useful Improvement in Negattive-Pole Accumulator-Electrodes, of which the following is a specification.

In the manufacture of storage batteries, 1t has become known that Othe shrinkage of the negative active material, and the subsequent loss of capacity, can be prevented by `adding to the active material certain For example, finely divided carbon, china-clay, cellulose and pumice stone have been proposed for ythat pur pose, and the use of these materials has been described in the Work of Dr. Sieg Die Accu- 'I2'vulatoren. Leipsig Verlag S. Hirsel 1901. The use of these substances has been known, but no .general law was know-n which ex. plained the difference of behavior of the negative active material in contact with these substances, and which'would enable a chemist or oneiskilled in the art to determine generally what substances Were suitable yfor that purpose. Furthermore, it was discovered that most of these substances, such as pumice-stone, cellulose, vand chinaclay, are decidedly inferior to finely divided carbon or lamp black, when employed for the purpose indicated. In addition, it lWas known that these substances, 4and more particularly the finely divided carbon, would produce an objectionable local action on the Enegative active material, resulting in its 4deterioration, Which action is easily explained in the case of the finely divided carbon by the fact that such material is electrochemic'ally active-that 'is to say, the carbon forms a galvanic couple with the negative active material. Such local action is, of course, undesirable, and such action becomes the more objectionable in its effects the greater the quantity of added inactive material. It is Well known, also, that the use of such additions results in the disintegrating and loosening of said negative active material, so that it is liable to expand outwardly from the grid and finally fall ofi". inasmuch as the use of mere retaining perforated sheets proved unsatisfactory,be cause the 4material inclosed in the perforated envelop would not expand against theresistance opposed to its growth by the I forated` Walls, grids have been devise 1n which the negative active material having inert substances added thereto` is caused to only partially fill the receptacles or spaces or compartments of the grid, so as to afford space or room for future expansion. See, for example, Patent Number 7 81,745, granted February 7', 1905, for improvement 1n negative pole plate. Also, German Patent Number 153,139, granted July 5, 1904. Obviously, however, this arrangement is characterized by certain disadvantages, inasmuch as the active material is not, at the beginning ofthe operation, in good electrical contact withthe grid, and is dependent for such contact upon the more or less irregular expansion caused by the addition of inactive substances. After considerable scientific investigation, I find that the reason why such inactive additions prevent the shrinkage .of the negative active material, is not a changed behavior of Vthe neoative .active -material, but simply the gessi-ng which must occur thereon and around the finely divided particles thereof at the passage of the electrical current during the charge; and if the addition, such as carbon, forms a galvanic couple with the negative .active material, then this is also true during rest anddischarge. Based on this scientific investigation, I also discovered `that a substance can be used for preventing shrinkage of the negative active material, and for preventing the subsequent loss of capacity, which Vsubstance heretofore has not been known to be suitable for this purpose, namely finely divided lead dust, employed as an admixture tothe negative active material. Such substance, I find, offers many advantages, for lead dust is chemically nearly identical with the negative active material, and for this reason causes practically no local action of the active material. Furthermore, lead dust is a good conductor and does not increase the resistance of the electrode, nor does it make its composition heterogeneous. Aga-in, the gassing around its particles occurs only during the charge, and is limited to .that time, and hence its action occurs at the time when it is most needed, namely when the dissolution of spongy lead takes place by reason or the greater concentration of the electrolyte 1n the pores, and not during the d1scharge and ,rest of the battery. I also find that lead dust can be used either by itself or in conn bin'ation with finely divided carbon,t and 1n the latter case it permits the user to dispense with :more than half of the carbon -or lampl yblack which otherwise would be necessary to obtain the desiredeffect.

vtionfof lead dust lto the negative' active material, anl ordinarygrid with pellets completely filling the. compartments,` and with a retaining perforatedenvelop of sufficient thickness, the battery Works satisfactorily,

and the contained negative active material does not show any shrinkage, Which result Was heretofore not possible. In this way. an obvious economy of space 1s obta1ned, as

distinguished from the devices' heretofore employed, and the electrode is not dependent for'a good contact of the negativeactive material With the' grid upon the eii'ect of the inactivel admixtuies.. Obviously, it will make no essential difference in the carrying` out of myinvention whether the retaining envelop is made of hard rubber, lead, or some other suitable material, and it' it 'is made of lead, which I find is a good material because of its good conductivity, it may be cast 'in one piece with the grid, or riveted or burned thereto.

In the accompanying drawings, Figure 1 is a diagram of a storage battery having negative-pole plates A, embodying the principles of my invention. Fig. 2 is an enlarged vertical section of one of said plates. Fig. 8 is a face View of a fragment of the plate, showing the grid and sections of active material in section. Fig. 4 is a-face view or side elevation of the plate on a smaller scale.

As thus'illustrated, the' said battery can be ofany suitable, known or approved 'construction. The negative-pole plates A are., however, provided with a negative active material'containing lead dust as-an admixture thereto.v The said negative active ma-- teral may be prepared or mixed in any suitable manner, and the lead dust is preferably tivo per cent. of the entire quantity of pastel Tlze materials for the paste can all .be mixed dry, including. tite tvvo per cent.

of lead du'st, and the liquid can then be added to the mixture. Negative active ma terial (sponge lead) of this character does not tend to shrink even if completely cov-4 ered by an envelop, While the envelop pre- In addition, I vfind that with the admixture of lead dust in ve'nts its expansion outside-of the grid during use of the battery. The leaddust doesmanner stated.- The said pellets or Sections of the said active material, Whenthus in- Closed in a perforated lead envelop, are in Agood electrical contact With the grid, and suc-h contact does not change, as the negative active material does not shrink and cannot freely and deleteriously expand, there beig,.theref ore, no consequent loss of capacity. By 4using the lead dust, the conductivity of the plate or electrode 'is not reduced, as previously explained.

As I say, I find that good results are obtained when lead dust is employed in the proportion of two per cent. of the entire quantity of paste. It is obvious, however, that the proportions can be varied Without departing from the spirit of my invention.

'Broadly considered, it will be seen that my invention consists of a negative active material having an admixture of lead dust.

That I claim as my invention is:

l. In a storage battery, a negative active material containing a small percentage of lead dust as an admixture thereto, as set forth.

2. In a storage battery, a negative pole electrode, comprising negative active material containing a small percentage of lead. dust as an admixture tlereto, and a pair of perforated lead plates inclosing said 11egative active material, forming a'combined grid and containing envelop for the same, as set forth.

In a storage battery, a negative element comprising a perforated envelop member, active material completely filling said y envelop member, vsaid active material con taining a small percentage ot lead dust.

Signed by ine-at Chicago, Illinois, this lstV 

